1. Field of the Invention
The present invention relates to an extendable built-in antenna unit for a mobile device, and more particularly to an extendable built-in antenna unit for a mobile device serving as a combination of embedded antenna and external antenna.
2. Background of the Related Art
Generally, a mobile device is a mobile telecommunication application having a variety of functions, for example telecommunication, network connections, and digital broadcast reception. The mobile device has an antenna for improved telecommunication.
The antenna is a wire used in radiating electric waves and/or inducing electromotive force using electric waves for wireless communication. An antenna unit may be electrically connected to a substrate and have a helical antenna and a whip antenna.
Conventionally, an antenna unit for a mobile device may be formed of an external antenna type, in which a helical antenna protrudes outwards from the mobile device. In the conventional external antenna type, a whip antenna may be received in the helical antenna or may protrude from the helical antenna. While external antenna type may provide good antenna performance, it may adversely influence the portability and external design of the mobile device.
FIG. 1 is a partial cross-sectional view of a conventional external antenna unit for a mobile device 100.
Referring to FIG. 1, the external antenna unit may include a whip antenna 120, a helical antenna 130, and an antenna receiving part 110. The helical antenna 130 may be formed in a spring pattern. A case 132 may surround the helical antenna 130. A grooved part 131 may be attached to the mobile device 100 and be configured to secure the helical antenna 130 to the mobile device 100. The case 132 may have a hole, through which the whip antenna 120 may pass.
The whip antenna 120 may be extractably and retractably mounted in the mobile device 100. For example, the whip antenna 120 may be inserted in the antenna receiving part 110 or may be extracted from the antenna receiving part 110. A stopper 121 may be formed on a lower surface of the whip antenna 120 and be configured to prevent the separation of the whip antenna 120 from the mobile device 100.
When the mobile device 100 is located in a strong electric field with good reception, the mobile device 100 may be used such that the whip antenna 120 may be retracted in the antenna receiving part 110. When the mobile device 100 is located in a poor electric field, the mobile device 100 may be used such that the whip antenna 120 may be extended outwards from the antenna receiving part 110 for improved performance.
If the helical antenna 130 is embedded in the mobile device 100, the resonance of the helical antenna 130 may disappear. Therefore, the helical antenna 130 is installed outside the mobile device 100, resulting in the mobile device 100 having a protruding portion of an antenna unit.
An embedded antenna unit (referred to as an intenna) has been developed in which a helical antenna may be installed in a mobile device. The embedded antenna unit may be incorporated by an inverted F-type antenna. The embedded antenna unit may provide portability and good external design. However, the embedded antenna unit has a difficulty in solving the problem that the resonance of the helical antenna may disappear when the helical antenna is installed in the mobile device, thereby suffering poor antenna performance.
Recent trends of mobile devices have moved towards good external design and miniaturization. Moreover, the mobile devices may be multifunctional, for example providing telecommunication, wireless Internet communication, navigation, digital broadcast reception, and Bluetooth communication. Accordingly, various frequency bands may be specified and a plurality of frequency bands may be utilized in a mobile device. Conventional external antenna unit have limitations in meeting the trends.